Study On Cultivation Of Musca Domestica Larvae And Extraction Process, Antibacterial Activity Of The Larval Proteins

In this paper，the cultivation conditions of musca domestica larvae werestudied，then detected the larval grow index and body protein．The yield andantibacterial activity of the larval protein were detected to optimize the preparationtechnology．The main results as follows．1．Effect of different cultivation conditions on growth and body protein content ofmusca domestica larvaeCultivating musca domestica larvae to4day-age with wheat bran asdiet．Wheat bran water content was modulated by adding water，breeding densitywas setted by inputting1day-age larvae to the diet，wheat bran was fermentedthrough adding different dose of bacillus subtilis，protein level of wheat bran wasimproved by adding different dose of whole lipid milk powder．The result showsthat：wheat bran of75%―80%water content is benefit to larval growth，the bodyprotein content in larvae of group75%is significant higher than group80%（P<0.05），but dry matter yield and F/G is no significant difference．The larvaegrows swiftly under the breeding density of12―20head/g wheat bran，withoutsignificant difference of body protein content（P>0.05），but F/G of20head/g isobviously lower than12and16head/g wheat bran．The wheat bran，which wasfermented by bacillus subtilis，can promote the growth of larvae，the body proteincontent and F/G in larvae of group0.3%is superior to group0.6%，but dry matteryield is only short of0.53%．The body protein content in larvae of group3%milkpowder in wheat bran is highest，but F/G is lower than control group and group2%（P>0.05），and a little more than group1%and4%．In this experiment，theoptimum cultivation conditions is as follows：the wheat bran content is75%，themusca domestica breeding density is20head/g wheat bran，the addictive amount ofbacillus subtilis is0.3%，the addictive amount of whole lipid milk powder is3%．2．Purification and extraction process of protein in musca domestica larvaeCultivating musca domestica larvae under the optimum cultivation conditions，protein was purified through tissue homogenate extraction，80℃hot water bath， Sephadex G50chromatography， and concentrated through dialysis， rotaryevaporation， freeze drying from musca domestica larvae， and identified theantibacterial ingredients by inhibition zone method，SDS-PAGE．The result showsthat：effect of three enrichment methods on antimicrobial activity of larval proteinis minor，the freeze drying is best．Molecular weight in4.08kD―10.45kD is themain antibacterial component of larval protein．Protein was prepared by spraydrying method from musca domestica larvae，and the optimum extraction processconditions in4℃environment were optimized through testing the yield andantibacterial activity of larval protein：the liquid-solid is4:1，the extraction time is0，the extraction liquid is PBS buffer．3． The research on induction and spray drying process of protein in muscadomestica larvaeOur research used a porcine E. coli K88as an inductor to cultivate muscadomestic larvae． The larvae was centrifuged to collect the protein, and theexpression of larval protein induction was measured by coomassie brilliant blue，inhibition zone method，Sephadex G50and SDS-PAGE．The results indicated thatthe total protein of treatment group was higher than control group (P>0.05)，andinhibiton zone diameter of treatment group was significantly higher than controlgroup (P<0.05)，in addition，the low dose of E. coli for larval protein induced effectwas the best．Then we used E. coli K88induced larvae as materials to measured thebest spray drying process parameter：inlet air temperature is140℃，approachingspeed is4r/min．In our research，the larval protein produced by spray dryingprocess was more sensitive in gram positive bacteria than gram negative bacteria．...